GBT 15-88 large semicircular head with tenon bolt tower crane bolt loose is what to do how to deal with the bolt loose problem

GBT 15-88 large semicircular head with tenon bolt tower crane bolt loose is what to do how to deal with the bolt loose problem

GBT 15-88 large round head with mortise bolt
Countersunk head screws are used to connect two or more objects and are indispensable in daily life or industrial manufacturing.
A fastener consisting of a head and a screw (a cylinder with external threads), used with a nut for fastening two parts with through-holes.
This type of connection is called bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the dowel bolt connection is a detachable connection.
Tower crane bolt loose how to deal with the problem of bolt loose
What is the cause of loosening of tower crane bolt? How to deal with the loosening of tower crane bolts? One possibility is that due to mechanical movement, the bolt is not loose enough to cause loosening; There is also the possibility of human negligence and failure to tighten the bolts. And the bolt anti loose is often not good with the bolt manufacturing accuracy is not high, anti loose design defects caused; Perhaps the bolt is installed and disassembled for many times, and the thread tooth slips.
Commonly used tm 60, 80 tm’s tower crane slewing bearing under the above is the slewing bearing, jib, balance arm, tower caps, cab, etc., its weight at 20 ~ 30 t, in the working state of tower crane, and vertical force produced by the dynamic load and bending moment, torque, so the vice of bolt connection requirements must be strictly in accordance with the provisions, the moment of tight, not too tight or too loose, too tight, The bolt will work for a long time at or close to yield strength, so that the bolt will soon fatigue and crack, resulting in fracture; Too loose, bolts and connecting pieces of relative movement, bolt head under repeated impact load and damage, resulting in serious tower crane accidents.
In the work of tower crane, it is often subjected to vibration, impact and variable load, and there are also seasons with great temperature changes. In this way, the friction force between screw inclined surfaces in bolt connection may disappear or decrease instantaneously. The repeated occurrence of this phenomenon will make the connection gradually loose, affecting the rigidity and tightness of the connection This may happen in any standard section of the tower body, and the bolt loosening in the above parts is considered to be a human factor. Self-climbing tower crane lift tower, before each tower crane jack-up, all connecting bolts to loosen the four or eight, top end, introduce the towers are standard, standard section will introduce standard section, under the rotation of the upper and lower bearings between bolting, and the lower section of tighten bolt connection does not generally neglect, tightened the immediately, and under the rotation of the upper bearing between the bolt In the tightening operation, it is often not tightened immediately because there is more than one jacking section plus standard section and jacking continues. In this way, it is possible that the connecting bolts of this layer are not tightened after the jacking is finally completed. The example found in the inspection is the example.
Bolt connection requirements for tower crane standard section:
* * *, tower crane work, a set of connection when the same joint pre-tightening force is too large, the deputy of axial force of bolt connection can vary widely, big bolt pretightening under heavy load for a long time, easy to produce fatigue fracture, were also found in the actual examination eight foundation bolt of a fracture, belong to this phenomenon. Attention should be paid to the consistency of the pre-tightening torques in installation. In field operation, due to the different strength of workers, the pre-tightening torques of the four column bolts are likely to be different, so the use of torque wrenches can be better controlled. To say the least, it should also be checked and adjusted by experienced shift masters.
Second, the fastening condition of all the connecting bolts should be checked once after the initial installation of the tower crane has been in operation for two shifts. In the next half a month or so, the bolts in the above parts should be inspected especially after the tower is raised. The position of the tower arm should also be rotated when checking. The bolts to be checked are directly below the position of the balance arm, so that it is reliable and effective to check whether the bolts are tightened.
Third, when the tower crane is transferred, all the tower body connecting bolts should be inspected in detail, derusting and lubrication. Cracks, wear, serious rust, overall or local plastic deformation and other abnormalities must be replaced. It is recommended to use it for no more than two times to avoid fatigue damage. This requirement, the existing tower crane may not meet the majority. If it is found that there is a shortage, it should not be processed and made by itself. Because the construction unit is not easy to control the processing quality and material of the perfect bolt, it should be better to buy it from the original tower crane production factory. The perfect bolt should be marked by the manufacturer and grade.
Tower crane safety monitoring and anti-collision system is used for multi-tower crane operation safety anti-collision alarm system in complex construction environment, can effectively prevent tower crane collision, prevent and reduce the collision in the collaborative operation of the group of machines, improve the construction safety of the site! The system is easy to install and operate, and can alarm and protect multiple tower cranes in a specific area of the site. At the same time, the anti-collision system of tower crane is a safe and effective dynamic monitoring system, which can help tower crane operators avoid serious and even fatal accidents caused by operation errors.